Interest in micro-robotics has increased rapidly in recent years. This is due mainly to technology development in the fields of microelectronics, micromachining, and microactuation. Currently, it is possible to build and test miniature systems that include numerous features, including sensors, actuators, and embedded control subsystems. The trend toward miniaturization is seen not only in industrial applications, but in medical applications as well.
There are many industrial applications for micro-robots. Micro-robots are suitable for work in small and inaccessible places; for example, in dismantling and reassembling factory pipelines, inspection of small environments, measuring various parameters, miniature manipulation, repairs, micromachining, complex molecular and atomic operations, and precision tooling, grasping, transport, and positioning with nanoscale motion resolution. Micro-robots that mimic insects have been developed, though currently such micro-robots are of limited use due to their size and low-level agility (see Fearing, R. S. et al. (2000) Proceedings of the 2000 IEEE International Conference on Robotics and Automation p. 1509–16). Mobile micro-robots, such as swimming robots, can be used for inspection and repair of thin pipes. Most of micro-robots concentrate on specific tasks. Micro-robots with small power requirements generally are suitable only for simple tasks, like moving forward and backward.
There are an increasing number of medical applications for micro-robots, such as in biological cell manipulation, blood-flow measurement, microsurgery of blood vessels and endoscopic surgery (a minimally invasive surgery). However, micro-robots have not been applied in laparoscopic or other minimally invasive surgery to date. Laparoscopic surgery avoids the trauma traditionally inflicted in gaining access to abdominal organs by using long, rigid instruments and cameras inserted into the body through small incisions. While minimally invasive surgical procedures reduce patient trauma, pain, recovery time, and hospital costs, there are several drawbacks to the technique. For example, there are regions of the patient that are inaccessible with current methods, and there is a lack of tactile feedback and limited dexterity and perception.
One micro-robot used currently in medical applications is a semi-autonomous endoscope device used during colonoscopy. The main advantage of this device is that the procedure generates only “internal” forces, unlike standard colonoscopy where the physician must provide high external forces to overcome acute intestinal bends. Two propulsion mechanisms have been proposed. One is based on “inchworm” locomotion, while the other uses “sliding clamper” locomotion (Menciassi et al. (2002) Proceedings of the 2002 IEEE/RSJ International Conference on Intelligent Robots, EPFL p. 1379–84).
Also, a miniature disposable imaging capsule has been developed. See, e.g., U.S. patent application Ser. No. 09/759,398. Such a capsule is swallowed by the patient and, with the natural movement of bowel, it moves through the gastrointestinal tract, and is passed naturally out of the body. The capsule transmits information (such as imaging information) to a receiver worn by the patient, which is later processed on a computer. The capsule consists of optical dome, lens holder, lens, illuminating LEDs, CMOS imager, battery, transmitter, and antenna. This device is used for colonoscopy. A similar device that is radio-controlled allowing for limited movement has been tested by researcher Annette Fritscher-Ravens at the University of London.
A device similar to that of Menciassi, et al., which is electro-pneumatically driven, has been developed. The advantage of this micro-robot is that it minimizes the contact between the colonoscope and the interior boundary of the colon, which makes the progression of colonoscope easier. The design uses three metal bellows disposed 120 degrees apart, while the position in the intestine is driven by three sensors positioned on a superior plate (Thoman et al. (2002) Proceedings of the 2002 IEEE/RSJ International Conference on Intelligent Robots, EPFL, p. 1385–90).
A Japanese company has developed miniature prototypes of endoscopic tools. One is an autonomous endoscope that can move through a patient's veins. Another prototype is catheter mounted with a tactile sensor to examine tumors for malignancy.
A prototype of a micro-catheter with active guide wire has been proposed. The active guide wires consist of hollow cable, and have two bending degrees of freedom (DOF) using an ionic conduction polymer film (ICPF) actuator on the front end. Use of an ICPF actuator provides the catheter with flexibility, good response, low voltage and safety (Guo et al. (1996) Proceedings of the 1996 IEEE International Conference on Robots and Automation (3):2226–31). A shape memory alloy (SMA) actuator has been proposed as well, but has some disadvantages, such as cooling, leaking electric current, and response delay (Fukuda et al. (1994) Proceedings of the 1994 IEEE International Conference on Robotics and Automation p. 418–23).
In addition, an ICPF actuator used in a fish-like robot having three degrees of freedom has been proposed for use in procedures involving aqueous media such as blood. The actuator is used as a propulsion tail fin and a buoyancy adjuster. The moving motion (forward, right, or left) is manipulated by changing the frequency of the applied voltage. The device is 45 mm long, 10 mm wide, and 4 mm thick, and might be used in microsurgery of blood vessels (Guo et al. (2002) Proceedings of the 2002 IEEE International Conference on Robotics and Automation p. 738–43). See also Mei et al. (2002) Proceedings of the 2002 International Conference on Robotics and Automation p. 1131–36.
A spiral-type magnetic swimming micro-machine has been developed. This device is driven by a rotating magnetic field, which implies that the system is wireless and does not require batteries of any kind. The micro-machine is composed of a cylindrical NdFeB magnet, ceramic pipes, and a spiral blade. The prototype length is 15 mm with a 1.2 mm diameter. It was shown that the device is suitable for miniaturization. The swimming direction of the machine can be controlled by changing the direction of the rotational magnetic field, while the velocity can be adjusted by changing the frequency of the rotating magnetic field. Tests have shown that in addition to running in a blood-like environment, the micro-machine has potential use in human organs (Ishiyama et al. (2000) International Symposium on Micromechatronics and Human Science p. 65–69).
Micro-robots are being used for performing automatic DNA injection autonomously and semi-autonomously through a hybrid visual serving control scheme. The system comprises an injection unit, an imaging unit, a vacuum unit, a microfabricated unit, and a software unit. A high precision, three DOF micro-robot is a part of the injection unit. The micro-robot is used to place precisely the injection pipette. In addition to being able to perform pronuclei DNA injection, the system is suitable for performing intracytoplasmic injection (Yu and Nelson (2001) Proceedings of the 2001 IEEE International Conference on Robotics and Automation p. 620–25).
There remains a need in the art for micro-robots that allow one to treat pathological organs while preserving healthy tissues, yet provide dexterity enhancement, enhanced perception, improved access, and remote treatment capabilities. The present invention fulfills this need in the art.